512 



NA TURE 



[October 6, 1923 



chemical analysis. The conception is fascinating in 

 its simplicity, and has dominated the greater part of 

 our soil work down to the present time, repeated 

 endeavours being made by variation in the methods 

 and intensity of the analytical attack to improve the 

 persistently low degree of correlation between analytical 

 data and crop results. Parallel with this at a later 

 date was developed the mechanical conception, which 

 found the major part of the explanation of the differ- 

 entiation of fertility in the physical properties of the 

 soil particles, while still later soil biology has asserted 

 its claim to provide the " simple solution." The work 

 of recent years, however, so brilliantly led in Great 

 Britain by Sir John Russell and his colleagues, leaves 

 us with no excuse for such restricted conceptions of 

 soil fertility, which must now be regarded as the index 

 of the equilibrium established by the mutual inter- 

 actions of a highly complex series of factors, the varia- 

 tion of any one of which may affect the interplay of the 

 whole, with consequent effect upon the rate or character 

 of plant growth. 



The problem of fertility being so complex, one might 

 perhaps be inclined to despair of attaining anything 

 really effective in soil advisory work, which must 

 necessarily be dependent upon rapid and somewhat 

 superficial examination. Such apparently is the view 

 held by the Ministry of Agriculture, if one may judge 

 by the conspicuous neglect of chemical and physical 

 science in recent extensions of advisory facilities. 



My own conception, however, of the present possi- 

 bilities of soil advisory work is more optimistic, and, 

 from experience covering the most diverse parts of 

 the country, I am confident that an extension of 

 facilities for soil advisory work would be of immediate 

 and progressively increasing benefit to the farmer. 

 The real difficulty at the moment is that for large 

 tracts of the country we lack the necessary data to 

 enable us to determine what is the " average soil " 

 for each particular area, and until provision is made 

 for specific soil work in these areas, which comprise 

 the whole of the great agricultural areas of the Mid- 

 lands, our advisory work relating to this raw material 

 of crop production must of necessity remain superficial, 

 and only too frequently ineffective. 



In no direction has the need for extended soil 

 advisory work become more evident in recent years 

 than in the revelation of the extent to which large 

 areas of our soils have become depleted of lime. Cases 

 come almost daily to our notice in which this lack of 

 lime is clearly the chemical " limiting factor," and the 

 annual waste due to unremunerative expenditure on 

 fertilisers on such land must indeed be very great. 

 In many cases, fortunately, the depletion has been 

 detected at a stage at which it is still economically 

 remediable, but in others, unfortunately, this is no 

 longer the case, and unless soil-survey facilities be 

 greatly extended, it is certain that large areas of our 

 land must steadily fall into the latter category, with 

 the inevitable development in the near future of a 

 problem of such magnitude as will require national 

 action for its solution. It is worthy of note also that 

 this problem will probably be accentuated rather than 

 diminished as a greater proportion of our arable land 

 reverts to grass. 



A further direction in which great scope remains for 



NO. 2814, VOU 112] 



the work of the soil adviser is in the economic manuring 

 of crops. Inadequate and improper manuring is still 

 widely prevalent, and the annual wastage of resourct > 

 thereby incurred' must represent a very large sum 

 A considerable part of this wastage is due to the wid* 

 spread use of proprietary compound manures, m«<i' 

 often than not compounded without any special rcf< r 

 ence to the soils upon which they are to be used, or 

 even without intelligent adaptation to the special needs 

 of the crops for which they are supplied. It is not 

 uncommon, indeed, to find mixtures of identical con. 

 position offered for the most diverse crops. In far too 

 many cases also the prices charged are extravagantly 

 disproportionate to the intrinsic value of the ingredients 

 of the mixture, and in all these various ways costs 

 of crop production are made higher than they need be. 



Passing on from soil and manuring, we come to 

 the sphere of seed and sowing problems, presenting 

 obviously abundant scope for advisory work. The 

 need for good and pure seed is axiomatic. Seed must 

 not only be good, however, but it mu.st also be of the 

 right kind, sown under proper conditions and at the 

 most suitable time, and the value of advi.sory guidance 

 on these points has always been recognised, especially 

 with reference to the choice between different varieties 

 of each particular crop. The variety tests carried out 

 on the various college farms and elsewhere have always 

 proved helpful in this respect in so far as they serve 

 to demonstrate the general characteristics of the 

 different varieties. Whether they have been equally 

 successful in measuring the cropping capacities of the 

 different varieties is more than doubtful, owing to their 

 restriction to single, or at most double, plots of a kind. 

 This has been recognised in the more elaborate schemes 

 devised for the purpose by the National Institute of 

 Agricultural Botany, which it is to be hoped may 

 furnish a practical scheme for more accurate quantita- 

 tive field tests in the future. 



Given good seed, the improvement of crop possible 

 through seed selection is perhaps not in general so 

 striking as that frequently obtainable by manuring, 

 but it may nevertheless be substantial, especially with 

 crops such as barley, where improvement of quality 

 may have a special value. There is also a rapidly 

 extending field for seed advisory work in connexion 

 with the laying down of land to grass for varying 

 periods. 



During the growth of the crop, advisory work is 

 largely restricted to the domain of diseases and insect 

 pests, the ravages of w^hich take incalculable toll of 

 our crops. I believe science can make no more directly 

 effective contribution towards the removal of at least 

 the technical difficulties of the farmer than the elabora- 

 tion of effective preventive measures against pests and 

 diseases. 



I must pass on, finally, to the utilisation of crop 

 products as food for animals, the line of work with 

 which my own personal interests and activities have 

 always been most closely associated. Looking back 

 over twenty years of advisory activity, I realise that 

 the position of the adviser in animal nutrition is 

 infinitely stronger to-day than when I first assumed 

 the role. 



With all the newer knowledge at his command, the 

 adviser in nutrition can now approach his work with 



